When the slider assembly is moving along the rails, the circulation maintaining device, the slider and the rails together form an enclosed circulation path which comprises a loaded path between the rails and the slider, two turning paths on two ends of the slider, and an unloaded path on the slider. Multiple rolling members are put in the circulation path so as to move endlessly along the enclosed circulation path such that the slider assembly can move smoothly on the rails.
The loaded path of the circulation path is composed of the roller maintaining plate, the first rails of the rail, the second rails for the slider. The roller maintaining plate and the slider are two elongate parts and have the same length. The roller maintaining plate usually has a top mainlining plate, a mediate maintaining plate and a bottom maintaining plate. In the conventional maintaining device, the connection portion is located at the two ends of the roller maintaining plate so as to be connected positioned by using pins, and this is disclosed in Taiwan Utility Model No. M322487, M310272 or M282068.
The shortcoming for the two above mentioned disclosures is that the area of the end face is too small so that the connection between the pins and the holes has a poor stiffness. The roller maintaining plate is easily deformed when the rolling members apply an outward force, so that the rolling members may not be easily kept in the circulation path. Besides, the connection position located at the ends of the roller maintaining plate may cause tolerance between the unloaded path and the returning path, interference is generated when the rolling members move between the returning path and the unloaded path.
In order to increase the stiffness of the connection between the slider and the roller maintaining plate, the two respective mediate portions of the top and bottom maintaining plates are fixed to the slider. Nevertheless, due to the narrow space, the mediate maintaining plate can only be fixed to the slider from ends thereof U.S. Pat. No. 7,341,378 and U.S. Publication No. 20050018933 disclose a long and high rigid plate such as a steel plate to be used to support the roller maintaining plate. This increases the cost required.
The present invention intends to provide a circulation maintaining device for a linear slide assembly to allow the mediate roller maintaining plate to have higher strength while no extra part is needed. Besides, the present invention reduces the number of molds for injection molding the circulation maintaining device.